Forces 2 - Momentum

Question 1

If a vehicle has a momentum of 20000 kg m/s and a mass of 1500 kg, at what speed is it travelling?

Answer 1

p = mvv = p/mv = 20000/1500p = 13.33 m/s

Question 2

If a vehicle has a momentum of 16000 kg m/s and a speed of 25m/s, what is its mass?

Answer 2

p = mvm = p/vm = 16000/25m = 640kg

Question 3

A car of mass 500kg is moving at a speed of 30 m/s. Calculate its momentum.

Answer 3

p = mvp = 500 x 30p = 15000 kgms-1

Question 4

What is the equation for moments?

Answer 4

moment = force x distance of force from pivot

or

moment = F x d

Moment in Nm
Force in N
Distance in M

Question 5

Describe what is happening in each of the pictures?

Answer 5

picture 1 - downward force (weight) is greater than upward force (air resistance)- sky diver is accelerating

picture 2 - air resistance is increasing so sky diver is acceelerating more slowly

picture 3 - sky diver has reached terminal velocity

Question 6

When a force acts at an angle to an object it produces a turning effect. What is this called?

Answer 6

A moment

The moment of a force about a fixed point or axis is the turning effect of the force about that point and is measured by the product of the force and the perpendicular distance from the point to the line of action of the force.

Question 7

A beam is laid across a pivot. 200 N is applied to one end of the beam at a distance of 2.5m from the pivot:

Answer 7

moment = 200 x 2.5 = 500 Nm

Question 8

A beam is laid across a pivot. 400N is applied to one end of the beam at a distance of 3.5m from the pivot.

Answer 8

moment = 400 x 3.5 = 1400 Nm

Question 9

We can use this equation to calculate the orbital speed:

Question 10

How fast would a satellite move if it was orbiting at a height of 100km and each orbit took 1.44 hours?